We are studying the photo receptors of the fruit-fly Drosophila melanogaster. The visual pigment (Rhodopsin-metarhodopsin) of Drosophila autofluoresces to blue and ultraviolet (UV) excitation. This is witnessed in vivo by the deep pseudopupil, or, on a cell by cell basis, after the cornea is optically neutralized under immersion oil. Cell specific differences in autofluorescence were used to map the receptor multiplicity in house flies. Now that so much more is known about the molecular genetics of fruit fly visual pigments, important issues need to be resolved in Drosophila. The PI has a productive program of research which has seen 8 papers since 1982 which acknowledge the IMR.